The foundations of buildings, which are generally made of concrete or other forms of masonry, are subject to cracking. Foundations may be slab foundations, or the walls of basements, on top of which building structures rest. Cracking may be caused by factors such as seasonal changes in temperature and humidity, exposure to ground moisture, mechanical pressure from supporting a structure built on top of the foundation, seismic activity, or other types of stresses. Often, after some number of years, the foundation cracks as a result of these stresses.
One aspect of foundation cracks is that they typically start small and then accelerate. In many cases, building owners are unaware of a crack until the crack has become severe, at which point the crack may be costly to fix, or may be irremediable.